a) Conservation of Mass:
Dalton's atomic theory asserts that atoms are indivisible and indestructible, and that in chemical reactions, atoms are rearranged but not created or destroyed. This leads to the law of conservation of mass, which states that the total mass before a chemical reaction is equal to the total mass after the reaction.
Example:
Consider the reaction between hydrogen (H) and oxygen (O) to form water (H2O):
2
H
2
+
O
2
→
2
H
2
O
2H
2
+O
2
→2H
2
O
Before the reaction, the total mass of hydrogen and oxygen is equal to the total mass of water formed. This illustrates the conservation of mass.
b) Definite Proportions (Law of Definite Composition):
Dalton's theory also proposes that compounds are composed of elements in fixed, definite proportions by mass. In other words, the ratio of the masses of the constituent elements in a compound is always constant.
Example:
Water (H2O) always has a fixed ratio of 2:16 (hydrogen to oxygen) by mass. Regardless of the source, any sample of water will always have this same ratio of hydrogen to oxygen.
c) Multiple Proportions (Law of Multiple Proportions):
Dalton's atomic theory further suggests that when elements combine to form different compounds, they do so in simple whole number ratios. This leads to the law of multiple proportions, which states that if two elements can combine to form more than one compound, the ratios of the masses of the second element that combine with a fixed mass of the first element will be ratios of small whole numbers.
Example:
Consider carbon (C) and oxygen (O). They can form two different compounds: carbon monoxide (CO) and carbon dioxide (CO2). In CO, the ratio of carbon to oxygen by mass is 12:16 (simplified to 3:4), while in CO2, the ratio is 12:32 (simplified to 3:8). These ratios are small whole numbers (3:4 and 3:8), illustrating the law of multiple proportions.